中性点直接接地运行是限制（）的措施之一。
A、设备过电压
B、操作过电压
C、工频过电压
D、谐振过电压
参考答案：B
如果一棵二叉树结点的先根遍历序列是A、B、C，后根遍历序列是C、B、A，则该二叉树结点的中根遍历序列（）。
A．必为A、B、C
B．必为A、C、B
C．必为B、C、A
D．不能确定
Sometimes I was thinking about _______ my own how I could make friends with a man who had little _______ common with me.
A．with; in
B．in; in
C．on; on
D．on; in
